Siphon tubes (also known as siphon strings or velocity tubes) are pipes having a relatively small diameter that are placed in natural gas wells to provide for removal of liquids (such as water) that might otherwise collect at the bottom of a well and thus impede the flow of gas from the well. Siphon tubes may be made from metal or polymeric materials, but it is desirable to use siphon tubes made from polymeric materials, as these can be formed into single tubes and can be spoolable, which facilitates transport, storage, and installation of the tubes. Metal siphon tubes also tend to be heavier and bulkier than their polymeric counterparts. Additionally, since many of the chemicals that exist naturally in wells or are typically used in well treatment are corrosive, it is often necessary that metal siphon tubes be made from expensive steel alloys. Metal siphon tubes also tend to have a rougher inner surface than polymeric tubes having the same inner diameter, which can impede fluid flow through the tubes.
Despite their advantages, current polymeric siphon tubes, which are typically made from high density polyethylene, generally can be used to a maximum depth of about 500 to 550 meters as pipes made from these materials lack the strength to support themselves at greater depths. Current polymeric siphon tubes have a tendency to creep to a substantial degree, which leads to constant increases in the length of the tube under its own weight as it hangs from the top of the well. Accurate positioning of the siphon tube in the well is important for proper operation, as a tube that is too short will not reach the liquids that accumulate at the bottom of the well and a tube that is too long can become wedged into the walls or bottom of the well or fill with mud or slit from earth at the bottom of the well, which can lead to partial or full blockage. Therefore, it would be desirable to obtain a polymeric siphon tube that has little or no creep and that can be used at depths greater than 500-550 meters when needed.